Photoelectrolysis of aqueous electrolytes by radiation to produce hydrogen and oxygen involves a process whereby light absorbed in one or both electrodes of an electrochemical cell generates electron-hole pairs (excitons). The excitons are separated and injected into the electrolyte at the photocathode and photoanode, respectively, to produce reduction and oxidation reactions. Photoelectrolysis can be used as a way to convert solar energy into chemical energy and as a way to store the energy for later use.